Spectral and thermal studies on mixed lignad complexes of zinc(II) and cadmium (II) with diethyldithiocarbamate and 2,2′-bipyridyl/1,10-phenanthroline

Abstract

Mixed ligand complexes of zinc(II) and cadmium(II) with diethyldithiocarbamate (ddtc) as a primary ligand and pyridine (py), 4-picoline (4-pic), 2,2′-bipyridyl (bpy), 1,10-phenanthroline (phen) as secondary ligands have been prepared and characterized by elemental analysis, thermogravimetric (TG) studies, infrared and1H-NMR spectral data. The general formula of cadmium(II) complexes are (L)2 Cd(ddtc)2 and (L-L)Cd(ddtc)2 while corresponding zinc complexes have (L)Zn(ddtc)2 and (L-L)Zn(ddtc)2 (where, L=py, 4-pic; L-L=bpy, phen) as evidenced by their elemental analysis and thermogravimetric studies. Infrared spectral data reveal that ddtc acts as a bidentate ligand in all cadmium complexes. However, in (L)Zn(ddtc)2 and (L-L)Zn(ddtc)2 complexes ddtc acts as bi-and unidentate ligand respectively. Octahedral geometry is assigned for all cadmium(II) complexes. Although (py)Zn(ddtc)2 and (4-pic)Zn(ddtc)2 complexes are known to have pentacoordinate zinc, yet the other mixed ligand complexes of Zn(ddtc)2 with bpy and phen have tetracoordinate zinc as evidenced by their infrared spectra. High resolution (300 MHz)1H-NMR spectra support the characterization of all complexes. TG data indicate that cadmium complexes initiate decomposition at high temperature in comparison with their respective zinc complexes. Thermograms of all mixed ligand complexes have two decomposition regions, out of which the first one corresponds to the removal of secondary ligands.